Refrigerating apparatus with defrosting controls



J. W. JACOBS A ril 9, 1963 REFRIGERATING APPARATUS WITH DEFROSTINGCONTROLS Filed June 26, 1961 Fig. 4

INVENTOR.

Fig.

DOOR O PERATED Fig. 3

0 w W r s A M J m Y B 3,984,529 REFRIGERATIIJG APPARATUS WKTH DEFRQSTINGCUNTRQifi James W. Jacobs, Dayton, Ghio, assignor to General MotorsQorporation, Detroit, Mich, a corporation of Delaware Filed June 26,1961, Ser. No. 119,376 Claims. (Cl. 62-156) This invention relates torefrigerating apparatus and more particularly to a low costself-defrosting refrigerator.

It is an object of this invention to so construct and arrange the partsin a refrigerator cabinet having a nonfrozen food storage compartmentand a frozen food storage compartment that both compartments can berefrigerated by a single evaporator which defrosts itself during eachofii cycle and which is fully isolated from the frozen food storagecompartment when the evaporator is defrosting.

Another object of this invention is to provide a refrigerator having twofood storage compartments to be maintained at different temperatureswherein a single evaporator is used for cooling both compartments andwherein the evaporator is located in the warmest part of thecompartments and is quickly self-defrosting during each off cycle.

More particularly it is an object of this invention to provide arefrigerator in which a single evaporator located in the uppermost partof the refrigerator is used for refrigerating the freezer compartment aswell as the main food storage compartment and wherein means are providedfor fully insulating the freezer compartment from the evaporator duringdefrosting of the evaporator.

These and further objects and advantages of the present invention willbe apparent from the following description, reference being had to theaccompanying drawing wherein a preferred embodiment of the presentinvention is clearly shown.

In the drawing:

FIGURE 1 is a front view with parts broken away showing somewhatschematically a preferred embodiment of the invention;

FIGURE 2 is a fragmentary sectional View on an enlarged scale showingthe thermostatically operated air valve;

FIGURE 3 is a circuit diagram showing the controls used; and

FIGURE 4 schematically shows the refrigerant circuit.

Referring now to the drawing wherein a preferred embodiment of theinvention has been shown, reference numeral 1t} designates an insulatedrefrigerator cabinet having an above freezing food storage compartment12, a freezing compartment 14 and a machinery compartment 13. Thecompartments 12 and 14 are cooled by means of a single evaporator 16located in the uppermost portion of the compartment 12. Conventionalaccess doors and 17 are provided for the compartments 12 and 14. Theevaporator 16 forms a part of a conventional refrigeration circuitincluding a compressor 20, a condenser 22 and a fixed restrictor 24, asshown in FIGURE 4.

A thermostat 26 having its temperature sensing bulb located on theevaporator 16 controls the compressor. The thermostat 26' operates adouble-throw switch 28 which closes the circuit to the compressor 24)when the evaporator temperature exceeds 34 F. and maintains the circuitclosed until the evaporator temperature drops to 0 F., at which time thethermostat opens the circuit to the compressor, and turns on a light orlamp 3t? for a purpose to be discussed more fully hereinafter. Thesetemperature values are given for illustration only and may be varied tosuit design requirements. A conventional door 3,31,5Z6 Patented Apr. Q,1963 are operated switch 31 is arranged in the control circuit as shownin FIGURE 3 and serves to turn on the light 30 whenever the door 15 isopened.

The freezing compartment consists of an insulated food storage chest 46disposed in the upper part of the food compartment 12 directly beneaththe evaporator 16. Whenever the evaporator :16 is cold enough to producerefrigeration, a portion of the cold air leaving the evaporator isallowed to enter the freezer chest through an air inlet opening 42 whichis provided with an air valve or damper 44 which closes so as to preventair leaving the evaporator from entering the freezer compartment 14 whenthe temperature of the evaporator 16 exceeds a predetermined value.

The control for the damper 44 consists of a bimetallic actuator 46having its one fixed end arranged in thermal exchange relationship withthe first two passes of the evaporator 16. The movable free end of thebimetallic element 46 has a chain or linkage mechanism 48 securedthereto and to the air valve 44 for raising the air valve at lowevaporator temperatures and lowering the air valve so as to close theopening 42 at high evaporator temperatures.

During a normal run cycle, the evaporator temperature is low enough tocool the bimetallic element 46 and deflect it sufficiently to open theair valve to the freezer compartment. This allows flow of cold air intothe freezer compartment 14- as well as into the food compartment 12. Thethermostat 26 stops the refrigeration systern when the temperature ofthe evaporator reaches a predetermined low value such as zero degrees.When the thermostat has stopped the compressor, the evaporator 16quickly starts Warming up and the relatively warm liquid refrigerant fedinto the evaporator from the condenser 22 serves to quickly warm up thatportion of the evaporator to which the bimetallic element 46 responds soas to cause the bimetallic element 46 to close the air valve 44. Withthe compressor stopped and the air valve 14 closed, the evaporator 16will only be in thermal exchange relationship with the air from the foodcompartment 12. As pointed out hereinabove, when the compressor 20 isstopped, the electric light bulb 30 is energized and the heat from thisbulb tends to rise into the fiuelike space between the outer wall of thefreezer chest 14 and the inner wall of the main cabinet 10. Thus, thislight not only induces increased circulation of the relatively warm airfrom the food compartment over the evaporator 16 but also adds heat tothe air circulated over the evaporator 16 to further facilitate thedefrosting of the evaporator.

The food compartment '12 may be provided with the usual type of foodsupporting shelves 50 and the freezer chest can be provided with shelves52 which serve to sup port ice trays 54- in the path of the aircirculating from the air inlet 42 to the air outlet 45. In order tosimplify this disclosure, the usual hydrators, meat storage drawers,etc., have been omitted, whereas it is obvious they could be used.

The defrost water can be disposed of in any conventional manner in sofar as certain aspects of the invention are concerned. For a low costrefrigerator a drip tray 56 supported on top of the freezer chest 14directly beneath the evaporator 16 is provided as shown. A drain leadsfrom the lowermost part of the tray 56 into a removable defrost watercollecting receptacle 58 located on one of the shelves 5%. Such anarrangement makes possible a low cost refrigerator which isselfdefrosting and does not require expensive features, such as defrostheaters, insulated defrost water drain lines, bug traps, defrost waterdrain heaters and the like.

The damper 44 is provided with an auxiliary air flow nose,

control member 60 which partially restricts the air flow to thecompartment 12 when the bimetallic element 46 lifts the damper 44- todirect cold air into the freezer compartment. When the damper 44 closesthe inlet opening 42 during the defrost cycle, the member 60 moves toreduce the restriction to flow of air from the high temperaturecompartment over the evaporator.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. In a refrigerator, a cabinet having an insulated food storagecompartment therein, an evaporator within said compartment adjacent thetop wall of said compartment, means for supplying liquid refrigerant tosaid evaporator including a compressor and a condenser, means forming aninsulated frozen food storage chest located directly beneath saidevaporator, said chest including an insulated upper wall serving toinsulate the contents of said frozen food storage chest from saidevaporator, the space between the top of said frozen food storage chestand said top wall of said insulated compartment forming an air line,said frozen food storage chest having an air inlet communicating withsaid flue and having an air outlet communicating with said flue, adamper for controlling the flow of air through said inlet, thermal meansresponsive to the temperature of a portion of said evaporator foroperating said damper in response to predetermined changes in thetemperature of said evaporator, a light bulb disposed within said foodcompartment adjacent the inlet to said flue, thermal means responsive torefrigeration requirements for initiating operation of said compressorwhen refrigeration is required and for stopping the operation of saidcompressor and initiating operation of said light when no refrigerationis required, a door for said insulated food storage compartment, andswitch means operated by said door for energizing said light in responseto opening of said door.

2. In a refrigerator, a cabinet having an insulated food storagecompartment therein, a cooling element Within said compartment adjacentthe top wall of said compartment, means forming an insulated frozen foodstorage chest located directly beneath said cooling element, said chestincluding an insulated upper wall serving to insu late the contents ofsaid frozen food storage chest from said cooling element, said frozenfood storage chest having an air inlet and an air outlet, said air inletbeing arranged to receive air leaving said cooling element, a damper forcontrolling the flow of air through said inlet, thermal means responsiveto the temperature of a portion of said cooling element for closing saiddamper at cooling element temperatures above a predetermined value,means responsive to refrigeration requirements for initiating cooling ofthe air by said element when refrigeration is required and for stoppingthe cooling of air and initiating defrosting of said cooling elementwhen no refrigeration is required, a light bulb in said compartment, andmeans for energizing said light bulb when said compressor is deenergizedso asto add heat to said compartment.

3. In a low cost self defrosting refrigerator, a cabinet having aninsulated food storage compartment therein, an evaporator within saidcompartment adjacent the top wall of said compartment, means including acompressor and condenser for supplying liquid refrigerant to saidevaporator, means forming an insulated frozen food storage chest locateddirectly beneath said evaporator, said chest including an insulatedupper wall serving to insulate the contents of said frozen food storagechest from said evaporator, said frozen food storage chest having an airinlet and an air outlet, said air inlet being arranged to receiverefrigerated air leaving said evaporator, a damper for controlling theflow of refrigerated air through said inlet, thermal means responsive tothe temperature of a portion of said evaporator for closing said damperin response to a predetermined increase in temperature of saidevaporator, a light bulb disposed within said food compartment, thermalmeans responsive to refrigeration requirements for initiating operationof said compressor when refrigeration is required and for stopping theoperation of said compressor and initiating operation of said light whenno refrigeration is required, said last named thermal means serving toinitiate operation of said compressor only at evaporator temperaturesabove freezing whereby said evaporator is defrosted during each oficycle.

4. In a refrigerator, a cabinet having an insulated food storagecompartment therein for storage of unfrozen foods, an evaporator withinsaid compartment adjacent the top Wall of said compartment, meanssupplying liquid refrigerant to said evaporator including a compressorand a condenser, means forming an insulated frozen food storage chestlocated directly beneath said evaporator, said chest including aninsulated upper wall serving to insulate the contents of said frozenfood storage chest from said evaporator, the space between the top andsides of said frozen food storage chest and said top and side Walls ofsaid insulated compartment forming an air flue, said frozen food storagechest having an air outlet communicating with said flue and having anair inlet communicating with said fine, a damper for controlling theflow of refrigerated air through said inlet, thermal means responsive tothe temperature of a portion of said evaporator for closing said damperin response to a predetermined increase in temperature of saidevaporator, and thermal means responsive to refrigeration requirementsfor initiating operation of said compressor when refrigeration isrequired and for stopping the operation of said compressor when norefrigeration is required.

5. In a refrigerator, a cabinet having an insulated food storagecompartment therein, an evaporator within said compartment adjacent thetop wall of said compartment, means supplying liquid refrigerant to saidevaporator including a compressor and a condenser, means forming aninsulated frozen food storage chest located directly beneath saidevaporator, said chest including an insulated upper wall serving toinsulate the contents of said frozen food storage chest from saidevaporator, the space between the top and sides of said frozen foodstorage chest and said top and side walls of said insulated compartmentforming an air flue, said frozen food storage chest having an air outletcommunicating with said flue and having an air inlet communicating withsaid flue, a damper for controlling the flow of refrigerated air throughsaid inlet, thermal means responsive to the temperature of a portion ofsaid evaporator for closing said damper in response to a predeterminedincrease in temperature of said evaporator, and thermal means responsiveto refrigeration requirements for initiating operation of saidcompressor when refrigeration is required and for stopping the operationof said compressor when no refrigeration is required, said last namedthermal means including a thermostat responsive to the temperature ofsaid evaporator.

References ited in the file of this patent UNITED STATES PATENTS1,501,874 Wardenburg July 15, 1924 1,727,777 Juneau Sept. 10, 19292,126,285 Schaaf Aug. 9, 1938 2,346,287 Borgerd Apr. 11, 1944

4. IN A REFRIGERATOR, A CABINET HAVING AN INSULATED FOOD STORAGECOMPARTMENT THEREIN FOR STORAGE OF UNFROZEN FOODS, AN EVAPORATOR WITHINSAID COMPARTMENT ADJACENT THE TOP WALL OF SAID COMPARTMENT, MEANSSUPPLYING LIQUID REFRIGERANT TO SAID EVAPORATOR INCLUDING A COMPRESSORAND A CONDENSER, MEANS FORMING AN INSULATED FROZEN FOOD STORAGE CHESTLOCATED DIRECTLY BENEATH SAID EVAPORATOR, SAID CHEST INCLUDING ANINSULATED UPPER WALL SERVING TO INSULATE THE CONTENTS OF SAID FROZENFOOD STORAGE CHEST FROM SAID EVAPORATOR, THE SPACE BETWEEN THE TOP ANDSIDES OF SAID FROZEN FOOD STORAGE CHEST AND SAID TOP AND SIDE WALLS OFSAID INSULATED COMPARTMENT FORMING AN AIR FLUE, SAID FROZEN FOOD STORAGECHEST HAVING AN AIR OUTLET COMMUNICATING WITH SAID FLUE AND HAVING ANAIR INLET COMMUNICATING WITH SAID FLUE, A DAMPER FOR CONTROLLING THEFLOW OF REFRIGERATED AIR THROUGH SAID INLET, THERMAL MEANS RESPONSIVE TOTHE TEMPERATURE OF A PORTION OF SAID EVAPORATOR FOR CLOSING SAID DAMPERIN RESPONSE TO A PREDETERMINED INCREASE IN TEMPERATURE OF SAIDEVAPORATOR, AND THERMAL MEANS RESPONSIVE TO REFRIGERATION REQUIREMENTSFOR INITIATING OPERATION OF SAID COMPRESSOR WHEN REFRIGERATION ISREQUIRED AND FOR STOPPING THE OPERATION OF SAID COMPRESSOR WHEN NOREFRIGERATION IS REQUIRED.